JF Ptak Science Books Quick Post
Here's a good, no-longer-missing missing part of entries for the virtually bottomless History of Holes section of this blog—blasting holes drilled into rock faces for tunneling, appearing in an article in the Scientific American Supplement, February 2, 1878. I've never considered the placement of the holes drilled through rock before, mostly I guess because I've never though about it before today--also I have no doubt that I would not have been able to figure out what sort of info was being represented in the small drawings if they were out of context. The circles and lines standing apart from any explanation or legend could've represented any number of things, from pole or column placement to fort construction, though blasting holes would've been far from my guess list of what these geometries were.
There are a number of tunnels under consideration, all of different lengths, through different media, of different dimensions, and so on, all of which come into play when considering drilling and blasting one's way through 20,000 or 50,000 running feet of mountain.
The article was dryly fascinating, particularly in the human elements. On average it seemed as though for the tunnels surveyed in the article that 15-30 feet of earth would be removed each day, which seems like a lot given the time and the space to work in. Most of the excavating faces seem to have been about 8' x 10', or about 80 square feet, and in that space there were usually six workers operating the drills at one time. That seems to me to be very very cramped quarters operating big and noisy machines generating a lot of dust, all of which was happening with not-great lighting with a questionable air supply. That was one tough job.
Comments